Transmitochondrial Cybrid Generation Using Cancer Cell Lines.

In recent years, the number of studies dedicated to ascertaining the connection between mitochondria and cancer has significantly risen. However, more efforts are still needed to fully understand the link involving alterations in mitochondria and tumorigenesis, as well as to identify tumor-associated mitochondrial phenotypes. For instance, to evaluate the contribution of mitochondria in tumorigenesis and metastasis processes, it is essential to understand the influence of mitochondria from tumor cells in different nuclear environments. For this purpose, one possible approach consists of transferring mitochondria into a different nuclear background to obtain the so-called cybrid cells. In the traditional cybridization techniques, a cell line lacking mtDNA (ρ0, nuclear donor cell) is repopulated with mitochondria derived from either enucleated cells or platelets. However, the enucleation process requires good cell adhesion to the culture plate, a feature that is partially or completely lost in many cases in invasive cells. In addition, another difficulty found in the traditional methods is achieving complete removal of the endogenous mtDNA from the mitochondrial-recipient cell line to obtain pure nuclear and mitochondrial DNA backgrounds, avoiding the presence of two different mtDNA species in the generated cybrid. In this work, we present a mitochondrial exchange protocol applied to suspension-growing cancer cells based on the repopulation of rhodamine 6G-pretreated cells with isolated mitochondria. This methodology allows us to overcome the limitations of the traditional approaches, and thus can be used as a tool to expand the comprehension of the mitochondrial role in cancer progression and metastasis.

Evaluation of two approaches to lysosomal acid lipase deficiency patient identification: An observational retrospective study.

BACKGROUND AND AIMS: Lysosomal acid lipase deficiency (LALD) leads to the accumulation of cholesteryl esters and/or triglycerides (TG) in lysosomes due to the lack of the enzyme codified by the LIPA gene. The most common symptoms are dyslipidaemia and hypertransaminasemia, together with manifestations common to other lysosomal storage disorders (LSDs), including visceromegalies and elevated plasma biomarkers. Alteration of the lipid-liver profile (LLP) has been widely applied as a criterion for LALD screening, but the usefulness of biomarkers has not yet been explored. Our purpose was to explore the utility of plasma chitotriosidase activity (ChT) and CCL18/PARC concentration in addition to LLP to identify LALD patients in an observational retrospective study of two different sample collections. METHODS: Biological samples refining: Collection 1 (primary hypercholesterolemia suspected) included unrelated individuals with hyperlipidaemia and without LDLR, APOB and PCSK9 gene mutations (Set 1), and Collection 2 (LSD suspected) included individuals without definitive LSD diagnosis (Set 2). We assessed plasma LLP (total cholesterol and its fractions, TG concentration and transaminases activities), as well as plasma ChT and CCL18/PARC. All subjects with anomalous LLP and/or biomarker levels were LIPA sequenced. RESULTS: Twenty-four subjects showed altered LLP and/or biomarkers. We identified two LALD patients (one homozygous and one compound heterozygous) and one carrier of a novel LIPA variant. CONCLUSIONS: The measurement of plasma ChT and CCL18/PARC combined with LLP will be a useful approach to identifying LALD patients in retrospective LALD patient studies.

Assessment of plasma chitotriosidase activity, CCL18/PARC concentration and NP-C suspicion index in the diagnosis of Niemann-Pick disease type C: a prospective observational study.

BACKGROUND: Niemann-Pick disease type C (NP-C) is a rare, autosomal recessive neurodegenerative disease caused by mutations in either the NPC1 or NPC2 genes. The diagnosis of NP-C remains challenging due to the non-specific, heterogeneous nature of signs/symptoms. This study assessed the utility of plasma chitotriosidase (ChT) and Chemokine (C-C motif) ligand 18 (CCL18)/pulmonary and activation-regulated chemokine (PARC) in conjunction with the NP-C suspicion index (NP-C SI) for guiding confirmatory laboratory testing in patients with suspected NP-C. METHODS: In a prospective observational cohort study, incorporating a retrospective determination of NP-C SI scores, two different diagnostic approaches were applied in two separate groups of unrelated patients from 51 Spanish medical centers (n = 118 in both groups). From Jan 2010 to Apr 2012 (Period 1), patients with ≥2 clinical signs/symptoms of NP-C were considered 'suspected NP-C' cases, and NPC1/NPC2 sequencing, plasma chitotriosidase (ChT), CCL18/PARC and sphingomyelinase levels were assessed. Based on findings in Period 1, plasma ChT and CCL18/PARC, and NP-C SI prediction scores were determined in a second group of patients between May 2012 and Apr 2014 (Period 2), and NPC1 and NPC2 were sequenced only in those with elevated ChT and/or elevated CCL18/PARC and/or NP-C SI ≥70. Filipin staining and 7-ketocholesterol (7-KC) measurements were performed in all patients with NP-C gene mutations, where possible. RESULTS: In total across Periods 1 and 2, 10/236 (4%) patients had a confirmed diagnosis o NP-C based on gene sequencing (5/118 [4.2%] in each Period): all of these patients had two causal NPC1 mutations. Single mutant NPC1 alleles were detected in 8/236 (3%) patients, overall. Positive filipin staining results comprised three classical and five variant biochemical phenotypes. No NPC2 mutations were detected. All patients with NPC1 mutations had high ChT activity, high CCL18/PARC concentrations and/or NP-C SI scores ≥70. Plasma 7-KC was higher than control cut-off values in all patients with two NPC1 mutations, and in the majority of patients with single mutations. Family studies identified three further NP-C patients. CONCLUSION: This approach may be very useful for laboratories that do not have mass spectrometry facilities and therefore, they cannot use other NP-C biomarkers for diagnosis.

Genetic Variants of LDLR and PCSK9 Associated with Variations in Response to Antihypercholesterolemic Effects of Armolipid Plus with Berberine.

BACKGROUND: Armolipid Plus (AP) is a nutraceutical that contains policosanol, fermented rice with red yeast, berberine, coenzyme Q10, folic acid, and astaxanthin. It has been shown to be effective in reducing plasma LDL cholesterol (LDLc) levels. In the multicenter randomized trial NCT01562080, there was large interindividual variability in the plasma LDLc response to AP supplementation. We hypothesized that the variability in LDLc response to AP supplementation may be linked to LDLR and PCSK9 polymorphisms. MATERIAL AND METHODS: We sequenced the LDLR 3' and 5' untranslated regions (UTR) and the PCSK9 5' UTR of 102 participants with moderate hypercholesterolemia in trial NCT01562080. In this trial, 50 individuals were treated with AP supplementation and the rest with placebo. RESULTS: Multiple linear regression analysis, using the response of LDLc levels to AP as the dependent variable, revealed that polymorphisms rs2149041 (c.-3383C>G) in the PCSK9 5' UTR and rs14158 (c.*52G>A) in the LDLR 3' UTR explained 14.1% and 6.4%, respectively, of the variability after adjusting for gender, age, and BMI of individuals. Combining polymorphisms rs2149041 and rs14158 explained 20.5% of this variability (p < 0.004). CONCLUSIONS: Three polymorphisms in the 3' UTR region of LDLR, c.*52G>A, c.*504G>A, and c.*773A>G, and two at the 5' UTR region of PCSK9, c.-3383C>G and c.-2063A>G, were associated with response to AP. These results could explain the variability observed in the response to berberine among people with moderate hypercholesterolemia, and they may be useful in identifying patients who could potentially benefit from supplementation with AP.

Promoter variant -204A > C of the cholesterol 7α-hydroxylase gene: association with response to plant sterols in humans and increased transcriptional activity in transfected HepG2 cells.

BACKGROUND & AIMS: The bile acid pool influences intestinal cholesterol absorption because this process is strictly dependent on micellar solubilization, which is disrupted by plant sterols (PS). Plasma lipid variation relates to promoter variant -204A > C (rs3808607) of the CYP7A1 gene encoding for 7α-hydroxylase, an enzyme for bile acid synthesis. We hypothesized that this polymorphism would be associated with variability in lipid responses to PS. METHODS: We investigated 67 subjects (31 AA and 36 AC + CC) with lipid responses to PS documented in two studies. To assess the functionality of the -204A > C variant, electrophoretic mobility gel shift assays were performed and luciferase reporter plasmids containing the promoter were transfected into HepG2 cells. RESULTS: Compared to AA-subjects, C-carriers showed significantly higher adjusted mean reductions in total cholesterol (0.14 versus 0.43 mmol/L, P = 0.042) and increases in lathosterol-to-cholesterol ratios (0.10 versus 0.75, P = 0.013). The C-construct caused a 78% promoter activity increase and gel-shift assays showed lower affinity for nuclear transcription factors, while in silico experiments predicted a binding site for inhibitory nuclear factors RXR-CAR. CONCLUSIONS: Results suggest that promoter -204A > C variant is associated with enhanced CYP7A1 activity. Increased intestinal bile acids and ensuing more efficient cholesterol absorption might explain why C-allele carriers show enhanced cholesterol lowering and increased feedback cholesterol synthesis to PS intervention.

Reliable low-density DNA array based on allele-specific probes for detection of 118 mutations causing familial hypercholesterolemia.

BACKGROUND: Patients with familial hypercholesterolemia (FH) have a high risk of premature cardiovascular disease (PCVD). Mutations in the LDL receptor (LDLR) gene and the R3500Q mutation in the apolipoprotein B (APOB) gene are known to cause FH, but lack of high-throughput methods makes routine genetic diagnosis difficult. The objective of this work was to develop a DNA array for large-scale identification of mutant LDLR alleles. METHODS: We developed a low-density oligonucleotide microarray to identify 118 DNA sequence variations (117 for the LDLR gene and 1 for the APOB gene). We verified specificity and sensitivity by analyzing 1180 previously sequenced DNA samples, and conducted a blind study screening 407 Spanish patients with a clinical diagnosis of FH. RESULTS: The DNA array confirmed the previous genotyping results in almost all cases. In the blind study, the microarray detected at least 1 mutation in 51% of the patients for whom clinical diagnosis was classified as certain according to Dutch FH-MEDPED criteria; it also identified mutations in 37% of those with a diagnosis of probable/possible FH, thus giving a definite diagnosis. Patients harboring null mutations had shorter PCVD-free survival times and higher relative risk of PCVD than patients with a missense mutation. CONCLUSIONS: The proposed DNA array allows large-scale population screening and provides molecular information regarding mutation type and its correlation with clinical severity of FH, which can be used to develop therapeutic strategies.

Screening of APOB gene mutations in subjects with clinical diagnosis of familial hypercholesterolemia.

Monogenic hypercholesterolemia is a group of lipid disorders, most of which have autosomal dominant transmission. Familial defective apoB (FDB) resulting from mutations in the APOB gene is a well-recognized cause of autosomal dominant monogenic hypercholesterolemia (ADMH). However, the frequency of FDB among patients with ADMH is not well established. The aim of our research was to screen for mutations responsible for FDB in subjects with a clinical diagnosis of familial hypercholesterolemia. We studied 408 patients from the Spanish Register of Familial Hypercholesterolemia, proportionally distributed among all Spanish regions. Abnormal SSCP patterns of the APOB gene were checked by DNA sequencing and restriction analysis. Three out of the 408 patients were carriers of the R3500Q mutation, and 2 subjects were carriers of the silent T3552T mutation; in both of these patients functional mutations in the LDL receptor gene were found. We conclude that FDB is not a common cause of ADMH in Spain; the R3500Q mutation is the only mutation in APOB causing FDB, and the LDL receptor binding domain of APOB is highly conserved in the studied sample.

Molecular characterization of familial hypercholesterolemia in Spain: identification of 39 novel and 77 recurrent mutations in LDLR.

Mutations in the low-density lipoprotein receptor (LDLR) gene cause familial hypercholesterolemia (FH), an autosomal dominant inherited disorder associated with an increased risk of premature atherosclerosis. The aim of this study was to characterize the LDLR mutations in a group of 476 apparently non-related Spanish FH patients. The promoter region and the 18 exons with their flanking intron sequences of the LDLR gene were screened by PCR-SSCP analysis and DNA sequencing. In addition, we tested for the presence of the mutation p.R3500Q in the gene coding for apolipoprotein B-100 (apo B-100). We found 77 mutations previously described, and 39 novel mutations affecting the LDLR gene: 8 missense, 5 nonsense, 15 frameshift, 5 splicing, 4 in frame, one nucleotide change in the non-coding sequence of exon 1, and one silent variant. We have identified al least one of these LDLR gene mutations in 329 subjects (69%). Four patients were homozygous, 4 patients were compound heterozygous, 48 patients were found to carry two different sequence variants in the same allele and 4 patients carried three different sequence variants in the same allele. Additionally, 4 subjects were carriers of the p.R3500Q mutation in the apo B gene. All of these findings indicate that there is a broad spectrum of mutations and sequence variants in the LDLR gene causing FH in Spain.

[Differences in clinical presentation between subjects with a phenotype of familial hypercholesterolemia determined by defects in the LDL-receptor and defects in Apo B-100]. / Diferencias en la presentación clínica en sujetos con fenotipo de hipercolesterolemia familiar por defectos en el receptor LDL y por defectos de la apo B-100.

INTRODUCTION AND OBJECTIVES: Familial hypercholesterolemia and familial defective Apo B-100 are phenotypically indistinguishable. At present they can be distinguished by genetic analysis. PATIENTS AND METHODç We compared the clinical features of 13 subjects with familial defective Apo B-100 and 39 subjects with familial hypercholesterolemia. We used data from first degree relatives to compare morbidity and mortality between the two groups. RESULTS: We found statistically significant differences in total cholesterol and LDL cholesterol, which were lower in the familial defective Apo B-100 group (TC = 357 37.3 mg/dl vs 415 79.7 mg/dl and LDLc = 270 34.2 mg/dl vs 355 72.4 mg/dl). We found no differences in xanthomas, corneal arcus, smoking status, vascular events, blood pressure, BMI or waist/hip ratio. There were no differences between the two groups in the proportions of patients with cardiovascular disease or patients who died. We found statistically significant differences between the groups (p = 0.023) in the mean age at first vascular event (familial hypercholesterolemia and first degree relatives: 45.3 19.9 years; familial defective Apo B-100 and first degree relatives: 51.5 20.8 years). CONCLUSIONS: We conclude that familial defective Apo B-100 results in clinically milder hypercholesterolemia than familial hypercholesterolemia, and that discerning between them could be helpful to stratify the risk in persons with hereditary hypercholesterolemia.

The apolipoprotein B R3500Q gene mutation in Spanish subjects with a clinical diagnosis of familial hypercholesterolemia.

Familial hypercholesterolemia (FH) and familial defective apolipoprotein B-100 (FDB) are autosomal codominant diseases characterized by elevated LDL cholesterol levels and premature coronary artery disease. Mutations of the LDL-receptor and apolipoprotein B genes, which affect the binding domains of their protein products, are the causal defects. Securing the diagnosis of these conditions by molecular assays is important because it mandates early intervention for coronary risk reduction. DNA screening for apolipoprotein B R3500Q gene mutation was performed in 913 unrelated Spanish individuals with a clinical diagnosis of FH using a modified polymerase chain reaction protocol and restriction enzyme genotyping. Thirteen FDB heterozygotes were identified (frequency of 1.4% in subjects with a clinical diagnosis of FH). The prevalence of hypercholesterolemic subjects with FDB in the general Spanish population was estimated to be as low as 2.8 x 10(-5) (95% CI, -3.1 x 10(-4) to 3.7 x 10(-4)). The ancestors of 11 out of 13 FDB carriers were from Galicia, a region of Celtic ancestry in Northwestern Spain. As the series included 100 unrelated subjects of Galician ancestry, FDB appears to be an important genetic cause of hypercholesterolemia in this region. All the R3500Q mutations were found on the same allele, assigned to haplotype XbaI-/MspI+/EcoRI-/3HVR48, suggesting that the mutant alleles are identical by descent in people from Spain, as observed in other Caucasian populations. In conclusion, the R3500Q mutation of the apolipoprotein B gene, a common cause of FH in central Europe, is infrequent in the general Spanish population, but it is common in Galicia.

A mutation (-49C>T) in the promoter of the low density lipoprotein receptor gene associated with familial hypercholesterolemia.

We have identified a mutation (-49C>T) in the low-density lipoprotein receptor (LDLR) gene in a Spanish familial hypercholesterolemia (FH) patient. The mutation maps within repeat 3 of the LDLR gene promoter. This region binds Sp1 and collaborates with repeat 2 in the regulation of LDLR gene by sterols. To evaluate whether the mutation influenced the activity of the promoter, luciferase reporter plasmids containing 296 bp of the proximal promoter region were constructed. In transient transfection assays in HepG2 cells, the mutation resulted in an 80% reduction of promoter activity. Also, gel-shift assays demonstrated that the mutation severely affects Sp1 binding. However, the mutated promoter still retains the ability to respond to low sterol concentrations. As the analysis of the LDLR gene did not reveal any other changes, we conclude that the -49C>T mutation is the cause of FH in the patient. The analysis of the proband's pedigree indicated that not all the members of the family having the mutation disclose a FH phenotype. These results support the view that factors other than the presence of the mutation are important in the determination of the clinical phenotype in FH.